Anti and Pro biotics

Rx: Antibiotic + 1 Cup of Yogurt

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Antibiotics are among the most frequently prescribed medications in modern medicine, available to cure minor, as well as life-threatening, infections. However, antibiotics can produce undesirable side effects, some of which are severe enough to compromise patients’ adherence to the full course of treatment. One of the most common is antibiotic-associated diarrhea (AAD), which occurs in up to 30% of patients who take antibiotics.[1]

A recent systematic review published in JAMA[2] suggests that adding probiotics (from pro and biota, meaning “for life”) to a course of antibiotics may lessen or even eliminate the onset of AAD. Probiotics—live bacteria and yeasts—are widely marketed to consumers in the form of capsules, powders, fermented milks, and yogurts. It’s not really clear how they work, but scientists believe that good types of bacteria have long lived in symbiosis with humans and that the positive health effects may have evolved over time.

One likely role for probiotic bacterial cultures is to help bacteria naturally found in the gut to re-establish themselves—particularly during and after a course of antibiotics.[3] An estimated 100 trillion microorganisms representing more than 500 different species inhabit every normal, healthy bowel. Most of these microorganisms are beneficial, keeping pathogens in check, aiding digestion and nutrient absorption, and contributing to immune function. A week-long course of antibiotics will destroy the bacteria causing the acute infection, but can also wipe out these beneficial microorganisms. As this delicate balance in the colon is disrupted, AAD may result.

To try to clarify the role of probiotics in defusing AAD, the JAMA researchers analyzed data from 82 randomized control trials that included children, adults, and the elderly. The most commonly used probiotic (57 studies) was some form of Lactobacillus; 16 studies used an exclusively yeast-based intervention. Among the 11,811 participants, those who took probiotics were 42% less likely to suffer from AAD. While many of the studies were of poor quality, the effect of the probiotics on AAD was sustained—and increased—when the analysis was limited to higher quality trials. Unfortunately, only half of the studies included in the review provided the name of the genus and species of the probiotic and few of the studies included the name of the antibiotic.[2]

Probiotics are available to consumers mainly in the form of dietary supplements (capsules, tablets, and powders) or in foods, such as yogurt, miso, and some juice and soy products, with the bacteria either naturally present or added during the manufacturing process. Most probiotics include bacteria similar to those naturally found in the gut and have names such as Lactobacillus or Bifidobacterium. A few common probiotics are yeasts, such as Saccharomyces boulardii—sometimes taken by patients to treat the diarrhea associated with antibiotic administration.

While foods such as regular yogurt, aged cheeses, and buttermilk naturally contain healthy bacteria, pasteurization can eliminate much of their bacterial presence. The recent boom in probiotic products reflects an effort to re-introduce bacteria to an enthusiastic audience, with companies seeking to attract health-conscious consumers by adding probiotics to products as diverse as yogurt, juices, muffins, and even pizza, as well as in dietary supplements. And Americans are apparently eating it up; spending on probiotic supplements approached $1.26 billion in 2010.[4]

Foods with probiotics are generally considered safe. However, the safety of probiotics has not been thoroughly studied[5] and more information is necessary about their effect on young children, the elderly, and people with compromised immune systems.[6] Side effects, if they occur, tend to be mild and digestive (such as gas or bloating). There is also some concern that by encouraging the growth of bacteria, probiotics could cause infections that need to be treated with antibiotics, especially in people with underlying health conditions.

Companies that sell probiotics claim they offer health benefits ranging from improved digestion and enhancing the immune system to preventing dental caries and colorectal cancer. Some of the claims are based on reputable scientific study. But others are unproven, and advertising claims are often exaggerated because probiotic supplements are regulated as food, not drugs, by the FDA. The quality of probiotic supplements also varies widely and, as a result, patients might have a difficult time choosing among a host of products.[7]

Bottom line? You might want to recommend a course of probiotics for patients who require a long course of antibiotics. If patients ask you about a specific probiotic, suggest they purchase only those that readily identify the bacterial strain, the appropriate serving size, and the expiration date. The further away the date, the more live bacteria the yogurt is likely to contain. Encourage patients to get their daily intake of probiotics from yogurt and other fermented foods instead of from pills or capsules, as the food products contain other needed nutrients such as calcium.


Jill Shuman, MS, ELS
Published May 14, 2012



  1. Barbut B, Meynard JL. Managing antibiotic associated diarrhoea. BMJ. 2002;324(7350):1345-1346.
  2. Hempel S, Newberry SJ, Maher A, et al. Probiotics for the prevention and treatment of antibiotic-associated diarrhea: a systematic review and meta-analysis. JAMA. 2012;307(18):1959-1969.
  3. D’Souza AL, Rajkumar C, Cooke J, Bulpitt CJ. Probiotics in prevention of antibiotic associated diarrhoea: meta-analysis. BMJ. 2002;324(7350):1361.
  4. Gelski J. Staking out probiotic claims: avoid drug implications and use well-researched strains. Food Website. Published September 28, 2010. Accessed May 12, 2012.
  5. Hempel S, Newberry S, Ruelaz A, et al. Safety of Probiotics Used to Reduce Risk and Prevent or Treat Disease. Executive Summary, Evidence Report/Technology Assessment No. 200. AHRQ Publication No. 11-E007-1. Rockville, MD: Agency for Healthcare Research and Quality; 2011.
  6. Ezendam J, van Loveren H. Probiotics: immunomodulation and evaluation of safety and efficacy. Nutr Rev. 2006;64(1):1-14.
  7. Donohue DC. Safety of probiotics. Asia Pac J Clin Nutr. 2006;15(4):563-569.